Determine which relation is a function.

A.
{(–3, 3), (–2, 3), (–1, 1), (0, 4), (0, 1)}

B.
{(–3, 2), (–1, 3), (–1, 2), (0, 4), (1, 1)}

C.
{(–3, 2), (–2, 3), (–1, 1), (0, 4), (0, 1)}

D.
{(–3, 2), (–2, 3), (–1, 2), (0, 4), (1, 1)}